Rolling mills employ elongated parallel rolls for exerting compressing force on metal feed stock, forming it into thinner strip or plate configuration. The rolls have reduced diameter end regions or "necks" which are journalled for rotation by roller bearings supported in a mill stand. Adjustable bearing chocking devices at each end of the roll hold the bearings in place and enable axial adjustment of bearing clearance. The chocking devices, upon being adjusted, are held in position by engagement with annular grooves provided in the roll necks.
In order to maintain required precision in the rolled product, the rolls must be frequently removed from the mill stand and reground to restore their surface finish. Useful life of a roll before refinishing its surface may be as short as a few hours. To minimize mill down-time during roll refurbishment operations, the bearing chocking apparatus should be easily installed, removed and adjusted.
Prior devices for chocking bearings on mill rolls have taken various forms. One type of device employs a pair of rings threaded together to provide an annular assembly of adjustable lengths. The assembly of threaded rings is positioned between a locking collar and the bearing to be chocked, and the rings are rotated to extend the length of the assembly until the bearing is properly chocked.
This approach presents difficulties in that the threaded rings are difficult to machine, and they tend to become contaminated with dust and other particles in operation, resulting in galling.
U.S. Pat. Nos. 3,912,345 and 3,966,282, issued Oct. 14, 1975, and Jun. 29, 1976, respectively, to Overton, disclose a mill roll chocking assembly having a segmented inner ring which is received in an annular groove in a roll neck. An outer ring is provided which can be slipped over the inner ring segments and into engagement with a bearing retainer. Wedge-shaped cam surfaces on the inner ring segments and the outer ring coact to axially move the outer ring as it is rotated relative to the inner ring, thereby axially adjusting the position of the bearing retainer and effecting chocking of the bearings. The inner ring is keyed to the roll neck to prevent relative rotation therebetween. The outer ring is bolted to the inner ring once the outer ring has been positioned to chock the roll bearings. While providing a distinct improvement over threaded ring assemblies, the device shown in these patents presents a disadvantage in that the inner and outer rings must be removed from the chocking assembly in order to allow the assembly to be slid off the roll neck inasmuch as the inner ring is located in the shaft groove. Removal of the rings requires unbolting them and rotating the outer ring to disengage the wedge segments of the outer ring from mating segments of the inner ring so as to allow the outer ring to be moved axially over the inner ring and off the assembly. The hinged inner ring must then be unlocked and removed from the shaft groove. A reverse sequence of steps is required in re-assembling the chocking device. Manipulations required in this procedure are cumbersome and labor intensive, particularly for large mills where the rings are heavy enough to require the efforts of two men using special lifting equipment. It is desired to provide an improved locking device using a pair of rings with mating wedged surfaces, but one in which the rings need not be removed from the chocking assembly to allow the assembly to be slid off the roll neck. This would significantly reduce the down-time required for roll refinishing and improve the efficiency of the mill.
A further disadvantage with the device of the patents is that inasmuch as the outer ring must be slid axially over the inner ring during assembly and disassembly, radially extending flange segments on the respective rings, which are provided with a series of holes for securing the rings when adjusted, must have a limited length around the circumference of the rings. This imposes a limit on the number of holes available for making adjustments. A ring structure in which the flange of both rings can be extended around their entire circumference would enable finer adjustments to be made.